Vacuum tube



Aug. 22, 1933.

E. G. MLfRPHY VACUUM TUBE Filed Oct. 24, 1928 Patented Aug. 22, 1933unirse s'rnrss PATsN f orifflci:N l

2 Claims.

The present invention relates to vacuum tubes being a special adaptationoi the method and means disclosed in my patent, Serial No. 1,699;- 011,dated January 15, 1929, for vacuum tube.

In the copending application above referred to, a general method orsystem was shown whereby the electrodes oi-a vacuum tube could becontrolled and regulated simultaneously or individually and selectively,as desired, by the insertion of removable cartridge.' elements. Theresults achieved by this system are' accomplished by merely moving orexchanging the wiring leads in the base of the vacuum tubo from onecartridge element or electrode tol the other. Many external controldevices and wiring are elminated by the method above indicated, 'whilethe greatly shortened leads to the electrode add also substantially tothe efficiency ci tubes oi the design and construction herein `reierredto, the present modification oi which has for its object the provisionoi a novel vacuum tube with self-inclosed means for varying or balancingthe electrostatic capacity between the electrodes ofthe tube.

Another object isto provide a vacuum tube of the type indicated withinsertable adjustable means for neutralizing or balancing theelectrostatic capacity oi the said electrodes with the option ofimmediately restoring the tube to its conventional operation andfunction by 'the withdrawal of theinsertable means;

Additional objects and advantages ci' the method employed will appearmore fully in the hereinafter described details when taken in connectionwith the accompanying drawing inwhich,

Figure l is a side elevation of the exterior of a vacuum tube embodyingmy invention;

Fig. 2 Vis a vertical sectionalY view talenvon line 2-2 of Fig. 1, withparts broken away;

Fig. 3 is a vertical section, similar to Fig. of a slightly modiied formof my invention;

Fig. 4 is an enlarged longitudinal vsection of the adjustable cartridgecondenser which is to be inserted in the base of the tube;

Fig. 5 is an enlarged sectional view of the cartridge resistance elementalso insertable in the base of the tube;

Fig. 6 is an elevational View of a tube similar to that shown in Figs. 1and 2, with thev addition of an insertable filament control cartridgeresistance in the base, and

Fig. 7 is a vertical sectional view, taken on line 7--7 of Fig. 6, partsbeing broken away.

In thedrawing wherein similar characters (Cl. Z50-27.5)

of reference indicate corresponding parts in the several views ci thepreferred forms of the in-V vention, A designates a vacuum tube havingan envelope 10 secured to a base 11, the enevelope being formedintegraiiy with Vthe glass press 12 60 in which latter are secured thesupporting rod 13 for the lainent 1li; the supporting rod 15 for thegrid 16, and the rod 17 which supports the anode or plate 18.

. To the bottom of the base 11 of the vacuum 65 tube Vare secured thecircuit-completing prongs which include the filament prongs 19, 20; thegrid prong 21 which `is connected to the grid by the conductrn` wire 22,and the anode prong 23 connectedto` the anode electrode by wire 24. Byinspection of Figs. 2 and 3, it will be seen that grid connecting wire22 is attached to one oi` the split clamping conductor elements 25, 26which are formed of metal and suitably fastened in registering holes inthe base 11, the anode 75 conductor wire being attached to element 26.The split clamping elements 25, 26 provide resilient gripping socketsfor the reception of theV insertable cartridge condenser B which isformed of a tube of suitable dielectric 277-having `metal plugs 28, 29at the ends Vthereof in which ytheplates or rods 30, 31 are in'ibedded.Metal caps 32 33 communicating with the metal plugs 28,

29 provide a means whereby the cartridge con denser may be inserted inthe metal clamping elements 25, 26. vThe cartridge condenser B hasametal sleeve 34 slidablecn the exterior of the dielectric` tube 27, thesleeve being engaged by an larm 35 secured to the bottom of theV base11, whereby when-the ycondenser B is inserted in the. socket provided bythe clamping elements 26, the arm 35, as shown in Fig.` 2, will contactwith thesleeve 34 and shift samefto .thel right or left according to thedirection in which Y the condenser is thrust,this being accom- 95plished with any convenient object such as a match, nail, pen handle,etc., etc.

1n the slightly niodied 'form of the invention shown in Fig. 3, thedisposition of the electrodes and the wiring therein is identical withthat illustrated in Fig. 2, the only difference in the two forms shownbeing that in Fig. 3 the sleeve 34 has integrally depending rod 3a whichis secured permanently tothe bottom oi the base 11 by small nuts 36 orin any suitable manner. 105 As in Fig. 2, the sleeve'Sa forms one of theplates ci the condenser B, the electrostatic capacity of which is variedby sliding the sleeve relatively to the inner plates or rods 30, 31.

The cartridge condenser B is slid to the right L10 or left through thefixed sleeve in the modication shown in Fig. 3. In Fig. 2, the sleeve34,

plate electrodes, together with the wiring thereion-is practically thesame as that shown in the tube illustrated in Fig. 2. In Figs. 6v and '7however, an additional convenience is provided in the form of aninsertable cartridgeresistanc'e C for the control of the lcathode yorfilament 14. For the reception of this` cartridge resistance, a secondpair of metal clamping elements 3.7, 38 are provided. The resistance Clike the cartridge condenser B consists of the usual tube of dielectric39 having'metal plugs 40, 41 connected by a small coil 42 of resistancewire. Metal capsx 43, 44 communicating with the metal plugs '40, 4lcomplete the element C which is also removably received between theclamping elements 37, 38.' l J In Figs. 2 and 3, the filament circuit iscoinpleted from prong 19, through wire 19', 4rod 13,

Y. filament 14, conductor 14 to prong 20. In the tube shown in Figs 6and 7, prongv 19 is connected by a wire 45 to clamping element 38 whencethe current passes through metal cap 44, metal plug 41, resistance42,-metal plug 40, metal cap clamping element 37, wire connected to rod13, Vlament 14, wire 14 to prong 20. In the formv of tube Vlastmentioned, the electrostatic capacity of thegrid and plate` electrodescan be varied or neutralized, while the filament may be suitableenergized without the aid of external control apparatus.

The function andoperation of the tubes illustrated anddescribed has beenin large measure indicated rfrom the foregoing description, the

- inter-electrode capacity of the electrodes of these tubes beingsusceptible of variation and the inter-electrode capacity coupling, ofvneutralization by thevmethod and means set forth. The tendency to`self-oscillation in circuits associated with the grid and anodeelectrodes of 'a thermionic valve, particularly circuits employingradio-frequency amplification and rcgeneration,is frequently anundesirable feature by reason of the distortionofthe signals received.The remarkable clearness of tone and general quietness of operation ofradio receiving sets employing the so-called neutralization prinvcipleis, of course, well known. It is most conveniently practical bythepresent method and means to vary or neutralize the grid-plateelectrostatic capacity of thermionic vacuum tubes without resorting tothe use of external means in the associated circuits, as heretoforeused. The method rnow shown may be employed in connection with any ofthe electrodes of the tubes besidesfthe usual grid-plate combinationabove referred to Vand illustrated, as will be readily understood. It isespecially to be noted that the envelope-of this tube and the electrodestherein are of conventional pattern as manufactured by any of thefactory methods now employed, and that if desired, these tubes may 'beused in their ordinary capacity at once by .merely thrusting out thecartridge condenser.

VAs pointed out `in the original system described in my Patent 1,699,011alluded to above,

into the base of the tube the control elementsV heretofore' usedexternally in the circuits associated with the tube electrodes.

The present modication of my invention, as is apparent Vto those skilledin this art, is susceptible of considerable variation and modification,and I do not accordingly wish to be understood as conning myself to theprecise details of construction set forth, save to the extent these arecircumscribed within the scope of the appended claims.

What I claim as new and Letters Patent is:

vLA thermionic valve having a plurality of electrodes in an envelope, abase secured to. said envelope, av variable cartridge condenserinsertably mounted in said base and having a makeand-break connectionwith two of said electrodes, and anr element in the base coacting with asleeve slidably mounted` on said condenser whereby the capacity of thecondenser and consequently the electrostatic capacity rof the two saidelectrodes may be varied.

2. A device of the character described comdesire to secure by prising aplurality rof electrodes in an envelope,

